<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .flexbox{
            display: flex; /*弹性盒模型布局 默认元素横向排列*/
            /* flex-direction: column; 竖直排列 */
            border-style: solid;
            border-width: 1px;
        }
        .flexbox div{
            width: 100px;
            height: 100px;
            background-color: red;
            margin: 20px;
        }
    </style>
</head>

<body>
    <div class="flexbox">
        <div ></div>
        <div ></div>
        <div ></div>
    </div>

</body>

</html>